The present invention relates to a molding material for photosensitive photographic materials, which is mainly comprised of a vegetable fiber, exhibits good external appearance, emits no offensive odor, and does not cause any problem with fog formation during storage when employed as a container for photosensitive photographic materials.
There are various types of molding materials employed for photosensitive materials. For instance, there are materials employed for imaging units such as cameras, and a body for lens-fitted film, resin canisters, cassettes for loading of rolled film strips, and the like.
These are molded, employing various materials in accordance with types, sizes, wound lengths, and uses of the employed photosensitive materials. Generally, however, said materials are divided into paper and plastics. In more detail, paper includes corrugated cardboard, paper board, laminated materials of paper with plastic film or metal foil, and the like. Molding materials for photosensitive materials, which are molded employing paper and/or plastics are required to be low cost and to cause no problems as waste when discarded or incinerated. Those which are molded employing paper cause no critical problem as waste. However, the strength is weak, and problems occur in which the size as well as wound length of photosensitive materials to be placed is limited and further critical problems occur in which during transportation, deformation an breakage tend to occur.
Those which are molded employing plastics exhibit high strength. However, problems occur in terms of cost as well as waste disposal. Those prepared by combining paper and plastics exhibit intermediate properties. However, problems also occur in disposal of combined plastic and paper materials when disposal requires separation the paper and plastics as waste, whereby, much labor is required.
As methods to overcome these problems, Japanese Patent Publication Open to Public Inspection No. 7-225453 proposes a light shielding container which is molded employing a mixture of a resin with a cellulose based fiber. However, when employing the molding materials described in the example, problems with external flatness and glossiness occur. In addition, it has been found that problems with the generation of offensive odor also result. Furthermore, it has been found that when it is used as a container for a photosensitive material, and said photosensitive material is stored in it over an extended period of time (for at least 6 months), problems occur in which photographic characteristics are adversely affected, and specifically, fog of said photosensitive material increases. Japanese Patent Publication Open to Public Inspection Nos. 61-225234 and 5-210217 also describe materials prepared by mixing a fiber with a thermoplastic resin. However it has been found that the same problems as described above occur.
An object of the present invention is to provide a molding material which exhibits excellent external appearance and emits no offensive odor, while overcoming the aforementioned problems. It is also an object to provide a molding material for photosensitive photographic materials, which gives no adverse effect on photographic performances, when employed as containers for photosensitive photographic materials. Another object is to provide a thermoplastic composition which exhibits excellent dimensional stability as well as excellent disposal properties as waste, even when employed in a thermoplastic composition comprising at least 50 percent of a cellulose based fiber.
Various shapes of molded products have been employed which employ molding methods such as injection molding, compression molding, injection-compression molding, extrusion molding, and the like, using a thermoplastic resin composition comprising a vegetable fiber as the main component. Such compositions are suitably employed for extrusion molding followed by machining, to produce, for example, base board and verandah, floor materials, handrails, materials in kitchens and bathrooms for house construction, materials for furniture, or board heartwood as interior finishing materials in cars. Wood flour filled vinyl chloride resins have been employed for similar uses. However, when said resins are employed, problems occur in which toxic gasses are generated during incineration in waste treatment, as well as during accidental fires.
Recently, the removal of vinyl chloride based compounds from waste has been demanded to overcome air pollution problems during incineration and the like, and materials which replace said compounds are urgently sought. Based on non-pollution, cost, ease of conversion, and the like, those which have received most attention are polyolefin resins such as polyethylene and polypropylene.
However, when a non-polar polyolefin resin is combined with a vegetable fiber with high polarity, it is technically difficult. to cause the resulting combination to exhibit features of each component as well as new functions. For example, vegetable materials such as wood flour and the like occasionally comprise, except for moisture, a large amount of components such as polysaccharides, lignin, tannin, and the like which tend to chemically and thermally undergo decomposition and deterioration. Though these can be removed, problems occur in which cellulose has no affinity with a polyolefin resin. In order to blend such components, a fairly large amount of energy is required. Due to that, after the completion of blending, the vegetable fiber as well as the resin is deteriorated.
Of conventional techniques, those in which a mixture consisting of a vegetable fiber and a thermoplastic resin in an amount of less than said vegetable fiber is employed, as the main component, include the following. Japanese Patent Publication Open to Public Inspection No. 54-72247 describes a method in which wood flour is subjected to thermal treatment at 160 to 260xc2x0 C. in advance, and a processing aid, such as a thermoplastic resin, is added to the resulting wood flour, is allowed to melt and impregnate the wood flour, and said process is carried out at a relatively high temperature over a relatively long period to decrease the water content of said vegetable fiber. However, problems have occurred in which the strength decreases due to the deterioration of the components of the wood flour. Further, listed as processing aids of the resin are those having a melting point of 40 to 250xc2x0 C. Of organic processing aids, some are not preferred due to low compatibility with polyethylene resin which results in a bleeding-out phenomenon and relatively large degradation of physical properties. Furthermore, Japanese Patent Publication Open to Public Inspection No. 63-112639 discloses a composition which is prepared by combining a polyolefin resin with mineral oil, synthetic oil and wax, an inorganic filler, or an organic filler comprising wood flour. However, when a mixture of mineral oil and synthetic oil, which tend to cause bleeding-out, is employed in molded parts, problems with external appearance have occurred. Japanese Patent Publication Open to Public Inspection No. 55-127451 discloses a composition comprised of polyolefin powder, and wood flour, calcium carbonate or talc. The use of polyolefin powder is a preferred method to improve hopper bridging as well as dispersibility. Furthermore, Japanese Patent Publication Open to Public Inspection No. 58-21755 discloses a composition prepared by combining polypropylene with wood flour as a lubricant. Listed as lubricants are higher alcohols and acid esters, as well as glycerin and fatty acid esters, and their functions are improvement in wettability of wood flour as well as polypropylene, enhancement of physical-properties and improvement in extrusion properties. Next, Japanese Patent Publication No. 58-56534 discloses a composition comprised of polyolefin resin and rosin or derivatives thereof, or petroleum resin, plasticizer and a vegetable fiber powder. A light shielding container for photosensitive materials is proposed which is prepared by mixing cellulose based fiber and resin described in Japanese Patent Publication Open to Public Inspection No. 7-225453 and molding the resulting mixture. However, it has been found that all of these inventions result in deterioration of the fibers during mixing with a vegetable fiber, and the strength as well as tenacity is insufficient.
An object of the present invention is to provide a molded product which, upon employing a resin component in combination with a vegetable fiber, generate no toxic gasses during incineration in waste treatment as well as during accidental fires, overcomes problems with degradation of a vegetable fiber, further is not likely to break when dropped, and exhibits excellent external appearance, and in addition a molding material which gives no adverse effects in photographic performances, when employed as a container for photosensitive photographic materials.
Item 1.
Molding materials comprising
a cellulose based fiber, and
a thermoplastic resin in an amount of less than said cellulose based resin.
wherein
when a 100 cm2 photosensitive material which is removed from an aluminum vessel having an inner diameter of 76 mm and a height of 50 mm, after said photosensitive material left standing at 23xc2x0 C. and 55% RH for 24 hours is placed into said aluminum vessel and is tightly sealed, and subsequently is left standing at 65xc2x0 C. for 72 hours, and thereafter, is cooled at 23xc2x0 C. and 55% RH for 12 hours, is designated as Sample A, and a 100 cm2 photosensitive material of the same type of said photosensitive material which is removed from an aluminum vessel having an inner diameter of 76 mm and a height of 50 mm after said photosensitive material left standing at 23xc2x0 C. and 55% RH for 24 hours and 4 g of said molding material left standing at 23xc2x0 C. and 55% RH for 24 hours are placed into said aluminum vessel and are tightly sealed, and subsequently are left standing at 65xc2x0 C. for 72 hours, and thereafter, are cooled at 23xc2x0 C. and 55% RH for 12 hours, is designated as Sample B, Sample A and Sample B are then subjected to white light exposure through a sensitometric step wedge and to the following photographic processing to obtain a fog density (fog density of Sample Bxe2x88x92fog density of Sample A) of the green-sensitive layer xe2x89xa60.2.
The pH is adjusted to 10.06 using potassium hydroxide or 20% sulfuric acid.
The pH is adjusted to 4.4 using aqueous ammonia or glacial acetic acid.
After adjusting the pH to 6.2 using aqueous ammonia or glacial acetic acid, the total volume is adjusted-to 1 liter by adding water.
The pH is adjusted to 8.5 employing aqueous ammonia or 50% sulfuric acid.
The inventors of the present invention have diligently investigated molding materials which may minimize the fogging problem. As a result, said inventors have found a molding material which exhibits surprising advantages in which fogging is not only minimized but also the generation of offensive odor as well as the degradation of external appearance is minimized.
Item 2
The molding material described in Item 1,
after 1 g of said molding material is left standing at 23xc2x0 C. and 55% RH for 24 hours, the resulting material is placed into a 30-cc vessel and tightly sealed, is further heated for 30 minutes in an oil bath maintained at 120xc2x0 C., and thereafter, the amount of furfural, generated in said vessel, is no more
than 10 xcexcg/g of the molding material.
Item 3
The molding material described in Item 1, and said thermoplastic resin comprises no halogen atom.
Item 4
The molding material described in Item 1, and said cellulose based fiber comprises a natural fiber.
Item 5
The molding material described in Item 4, and said natural fiber comprises a vegetable fiber.
Item 8
The molding material described in Item 1, and the molding material comprises at least one selected from the compounds represented by general formulas (I) through (V) or tetramethylolcyclohexanol,
xe2x80x83R1CSxe2x80x94Xxe2x80x94R2 or R1COxe2x80x94Xxe2x80x94R2xe2x80x83xe2x80x83(I)
in general formula (I), R1 represents a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an acylamino group, or an amino group, R2 represents a hydrogen atom, an alkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, a carbamoyl group, an amino group, or an amidino group, R1 and R2 may bond to form a ring, X represents xe2x80x94CH2xe2x80x94 or xe2x80x94NHxe2x80x94; 
in general formula (II), R3, R4 and R5 may be the same or different, and each represents a hydrogen atom, an alkyl group, an alkenyl group, an aralkyl group, an aryl group, or an acyl group, R6 and R7 each represents a hydrogen atom or an alkyl; 
in general formula (III), R8 represents a hydrogen atom, an alkyl group, or an aryl group, R8 may be a group which forms naphthalene ring together with a phenyl ring, xe2x80x9cnxe2x80x9d represent an integer of 2 to 4; 
in general formula (IV), R9 represents a hydrogen atom or a substituent, R10 represents a hydrogen atom or a substituent; 
in general formula (V), R11 and R12 each represents a hydrogen atom or a substituent, and R13 represents a hydrogen atom or an alkyl group, Z represents a hydrogen atom, an alkyl group, an aryl group, xe2x80x94SO2R14, or xe2x80x94SO2N(R14) (R15), R14 represents an alkyl group, an aryl group, or a heterocyclic ring group, and R15 is as defined above for R13, R13 and Z may be joined together to form a ring.
Item 15
The molded product molded employing the molding material described in Item 1.
Item 16
The molded product described in Item 15, and said molded product is a container for a photosensitive material.
Item 17
The molded product described in Item 16, and said molded product is a part of a lens-fitted film.
Item 18
The molded product described in Item 17, and said molded product is an external packaging member of a lens-fitted film.
Item 19
The molded product described in Item 18, and said molded product is a front cover or a rear cover of a lens-fitted film.
Item 20
A production method of a molding material, it is comprised of the following steps:
Cellulose based fiber together with a thermoplastic resin in an amount of less than said cellulose based fiber is kneaded,
wherein
when a 100 cm2 photosensitive material which is removed from an aluminum vessel having an inner diameter of 76 mm and a height of 50 mm after said photosensitive material left standing at 23xc2x0 C. and 55% RH for 24 hours is placed into said aluminum vessel and is tightly sealed, and subsequently is left standing at 65xc2x0 C. for 72 hours, and thereafter, is cooled at 23xc2x0 C. and 55% RH for 12 hours is designated as Sample A, and a 100 cm2 photosensitive material of the same type of said photosensitive material which is removed from an aluminum vessel having an inner diameter of 76 mm and a height of 50 mm after said photosensitive material left standing at 23xc2x0 C. and 55% RH for 24 hours and 4 g of said molding material left standing at 23xc2x0 C. and 55% RH for 24 hours are placed into said aluminum vessel and are tightly sealed, and subsequently are left standing at 65xc2x0 C. for 72 hours, and thereafter, are cooled at 23xc2x0 C. and 55% RH for 12 hours is designated as Sample B, Sample A and Sample B are subjected to white light exposure through a sensitometric step wedge and to the following photographic processing to obtain a fog density (fog density of Sample Bxe2x88x92fog density of Sample A) of the green-sensitive layer xe2x89xa60.2.
The pH is adjusted to 10.06 using potassium hydroxide or 20% sulfuric acid.
The pH is adjusted to 4.4 using aqueous ammonia or glacial acetic acid.
After adjusting the pH to 6.2 using aqueous ammonia or glacial acetic acid, the total volume is adjusted to 1 liter by adding water.
The pH is adjusted to 8.5 employing aqueous ammonia or 50% sulfuric acid.
Item 21
The production method of a molding material described in Item 20, and said kneading is carried out employing a banbury mixer.
A molding material characterized in comprising a mixture consisting of a vegetable fiber and a thermoplastic resin in an amount of less than said vegetable fiber as the main components and in satisfying the conditions set forth below:
Conditions:
When a 100 cm2 photosensitive material which is removed from an aluminum vessel having an inner diameter of 76 mm and a height of 50 mm after said photosensitive material left standing at 23xc2x0 C. and 55% RH for 24 hours is placed into said aluminum vessel and is tightly sealed, and subsequently is left standing at 65xc2x0 C. for 72 hours, and thereafter, is cooled at 23xc2x0 C. and 55% RH for 12 hours, is designated as Sample A, and
a 100 cm2 photosensitive material which is removed from an aluminum vessel having an inner diameter of 76 mm and a height of 50 mm, after said photosensitive material left standing at 23xc2x0 C. and 55% RH for 24 hours and 4 g of a molding material, comprised of a mixture of a vegetable fiber and a thermoplastic resin in an amount of less than said vegetable fiber as the main component, left standing at 23xc2x0 C. and 55% RH for 24 hours are placed into said aluminum vessel and are tightly sealed, and subsequently are left standing at 65xc2x0 C. for 72 hours, and thereafter, are cooled at 23xc2x0 C. and 55% RH for 12 hours, is designated as Sample B,
Sample A and Sample B are subjected to while light exposure through a sensitometric step wedge and to the following photographic processing to obtain a fog density (fog density of Sample Bxe2x88x92fog density of Sample A) of the green-sensitive layer xe2x89xa60.2.
The pH is adjusted to 10.06 using potassium hydroxide or 20% sulfuric acid.
The pH is adjusted to 4.4 using aqueous ammonia or glacial acetic acid.
After adjusting the pH to 6.2 using aqueous ammonia or glacial acetic acid, the total volume is adjusted to 1 liter by adding water.
The pH is adjusted to 8.5 employing aqueous ammonia or 50% sulfuric acid.
A molded product characterized in comprising a mixture consisting of a vegetable fiber and a thermoplastic resin in an amount of leas than said vegetable fiber as main components and of satisfying the conditions set forth below:
Conditions:
When a 100 cm2 photosensitive material, which is removed from an aluminum vessel having an inner diameter of 76 mm and a height of 50 mm, after said photosensitive material left standing at 23xc2x0 C. and 55% RH for 24 hours is placed into said aluminum vessel and is tightly sealed, and subsequently is left standing at 65xc2x0 C. for 72 hours, and thereafter, is cooled at 23xc2x0 C. and 55% RH for 12 hours, is designated as Sample C, and
a 100 cm2 photosensitive material which is removed from an aluminum vessel having an inner diameter of 76 mm and a height of 50 mm after said photosensitive material left standing at 23xc2x0 C. and 55% RH for 24 hours and 4 g of a molding product, which is obtained by crushing into pieces having a size of approximately no more than 5 mm a molded product having a specified shape comprised of a mixture consisting of a vegetable fiber and a thermoplastic resin in an amount of less than said vegetable fiber, left standing at 23xc2x0 C. and 55% RH for 24 hours, are placed into said aluminum vessel and are tightly sealed, and subsequently are left standing at 65xc2x0 C. for 72 hours, and thereafter, are cooled at 23xc2x0 C. and 55% RH for 12 hours, is designated as Sample D, Sample C and Sample D are subjected to white light exposure through a sensitometric step wedge and to the following photographic processing to obtain a fog density (fog density of Sample Dxe2x88x92fog density of Sample C) of the green-sensitive layer xe2x89xa60.2.
A thermoplastic composition comprising at least 50 percent by weight of a non-wood fiber as a natural fiber and a thermoplastic resin.
The thermoplastic composition described in any one of Items 1 through 7, characterized in that a mixture comprising at least a natural fiber and thermoplastic resin is obtained by kneading, employing a Banbury mixer.
The thermoplastic composition described in Item 8, characterized in that a mixture consisting of a natural fiber and a thermoplastic resin is kneaded, at a maintained temperature of 70 to 150xc2x0 C.
A molding material characterized in comprising a mixture consisting of a vegetable fiber and a thermoplastic resin having no halogen atom in an amount of less than said vegetable fiber as the main component, and satisfying the conditions described below.
Conditions
One gram of a sample is accurately weighed. Said weighed sample is conditioned at ambient conditions of 23xc2x0 C. and 55% RH for 24 hours, and thereafter is placed in a 300-cc vial, which is tightly sealed with an aluminum seal. After the vial is heated for 30 minutes in an oil bath maintained at 120xc2x0 C., the amount of furfural generated in the vial is no more than 10 xcexcg/g of the sample.
The present invention will be detailed below.
The molding material of the present invention comprises a cellulose based fiber as well as a thermoplastic resin in an amount of less than said cellulose based fiber.
Furthermore, the molding material has the following feature. When a 100 cm2 photosensitive material, which is removed from an aluminum vessel having an inner diameter of 76 mm and a height of 50 mm after said photosensitive material left standing at 23xc2x0 C. and 55% RH for 24 hours is placed into said aluminum vessel and is tightly sealed, and subsequently is left standing at 65xc2x0 C. for 72 hours, and thereafter, is cooled at 23xc2x0 C. and 55% RH for 12 hours, is designated as Sample A, and a 100 photosensitive material of the same type of said photosensitive material, which is removed from an aluminum vessel having an inner diameter of 76 mm and a height of 50 mm after said photosensitive material left standing at 23xc2x0 C. and 55% RH for 24 hours and 4 g of said molding material left standing at 23xc2x0 C. and 55% RH for 24 hours are placed into said aluminum vessel and are tightly sealed, and subsequently are left standing at 65xc2x0 C. for 72 hours, and thereafter, are cooled at 23xc2x0 C. and 55% RH for 12 hours, is designated as Sample B, Sample A and Sample B are subjected to white light exposure through a sensitometric step wedge and to the following photographic processing to obtain a fog density (fog density of Sample Bxe2x88x92fog density of Sample A) of the green-sensitive layer xe2x89xa60.2.
Further, the photosensitive material as described herein preferably represents ASA 400 color negative film, more preferably LV400 manufactured by Konica Corporation and more preferably represents the photosensitive material sample 101 described in Example 2 of Japanese Patent Publication Open to Public Inspection No. 8-69073.
The pH is adjusted to 10.06 using potassium hydroxide or 20% sulfuric acid.
The pH is adjusted to 4.4 using aqueous ammonia or glacial acetic acid.
After adjusting the pH to 6.2 using aqueous ammonia or glacial acetic acid, the total volume is adjusted to 1 liter by adding water.
The pH is adjusted to 8.5 employing aqueous ammonia or 50% sulfuric acid.
Furthermore, the molding material of the present invention is preferably comprised of at least 50 percent of a cellulose based fiber. Said cellulose based fiber is preferably comprised of a natural fiber, and the cellulose based fiber is preferably composed of only natural fibers.
The natural fibers as described in the present invention include vegetable fibers as well as animal fibers. The vegetable fibers imply any natural cellulose fibers obtained from wood fiber, stalk fiber, vein fiber, phloem fiber, seed fiber, and the like.
Listed as animal fibers may be silk and fibroin fiber from raised silkworms and field silkworms (for instance, tensan, sakusan, erisan, or the like), fibers from animals such as fibers from sheep wool and cashmere, fiber of camel wool, fiber of goat wool, fiber of alpaca wool, and fiber-like substances forming animal skin. The present invention is not limited to the examples of the fibers described herein.
Furthermore, all the natural fibers are preferably comprised of vegetable fibers. In addition, the natural fibers are preferably pulp.
The pulp as described in the present invention is a fiber extracted from plants, which is employed for paper making, and the main component of the fiber for paper making is cellulose. The chemical composition of the plant is rather complex. However, it is comprised of three main components of cellulose, hemicellulose and lignin. Other components include a small amount of protein and ash, such as silica and the like.
The vegetable fiber as described in the present invention means a fiber possessed by plant, and represents those obtained by directly drying the plant and those commonly marketed as pulp. Production methods of pulp include chemical pulping methods such as a Kraft pulping method, a sulfite pulping method, an alkali pulping method, and the like, and the pulp is bleached through a multi-step bleaching method. Furthermore, employed may be pulp itself or chemically treated pulp employing a crosslinking reaction or a mercerization reaction, known in the art.
Listed as raw materials employed in the aforementioned pulp production methods are needle-leaf trees such as pine, sugi (Japanese cedar), hinoki (Japanese cypress), and the like, broadleaf trees such as Japanese beeches, chinquapins, eucalyptuses, and the like, non-wood fibers such as flax, kozo or paper mulberry, mitsumata, bamboo, bagasse, and the like. However the present invention is not limited to these. Furthermore, in the proposition and the like on global environmental issues related to forest resources, the recycling of paper resources has been actively promoted. In such situations, those paper resources recycled as waste paper pulp may be employed which are produced in such a manner that used sheets of paper such as newspapers, weeklies, magazines, leaflets, which are collected from homes, firms and train stations, and paper trim waste, waste sheets and the like generated in bookbinding and printing plants are recycled through process of disaggregation, roughing, ripening, ink removal, cleaning, bleaching, and the like.
Plant materials for non-wood pulp production include not only true grasses but also herbaceous plants which do not form xylem in the part above the ground as well as all others generally called non-wood in the pulp industry. Listed as such plant materials may be, for example, shoot, flax, western flax, hemp which are composed of phloem fibers; ditch reed, sabai, esparto, rice plant, wheat, barley, rye, sugar cane, bagasse, and the like which are composed of stiff fibers; cotton, kapok, coconut husk, and the like which are composed of seed coverings; carnauba palm leave, Manila hemp, saizaru hemp, and the like which are composed of leaf fibers. Further, included are kozo or paper mulberry, mitsumata, unsized silk, mulberry, bamboo, rags which have been produced in a small scale as the raw materials for pulp.
As a useful non-wood pulp, kenaf pulp is preferably employed in the present invention. The kenaf is an annual plant cultivated in Thailand, China, Australia, and the like, and has attracted attention as a raw material for paper making pulp which may be employed instead of wood. In the 1950s, the United States Department of Agriculture first started an investigation on the application of kenaf. Since then, basic research as well as industrial research has been made, and a number of proposals have been presented. For example, in Japanese Patent Publication No. 2-42952, proposes to achieve an object to improve the insufficient surface smoothness possessed by a thick-walled fiber, by employing a kenaf chemical pulp together with a thick-walled fiber pulp. Furthermore, Japanese Patent Publication Open to Public Inspection No. 2-91297 proposes to accomplish a purpose to enhance the performance of a mechanical pulp by employing a kenaf pulp together with the mechanical pulp. Further, Japanese Patent Publication Open to Public Inspection Nos. 2-88286 as well as 2-92576 proposes to achieve a purpose to obtain a thermal printing sheet and paper for a pressure-sensitive copying sheet by employing kenaf pulp together with ordinary pulp. Still further, in Japanese Patent Publication Open to Public Inspection Nos. 6-262868 proposes to achieve an object to obtain a thermal transfer receiving paper.
In the present invention, an object of employing a helmilase enzyme, for example, a hemicellurasexylan decomposing enzyme is to decompose the xylan part of ligno cellulose, which is thought to bond white cellulose to brown lignin.
Accordingly, the decomposition of xylanhemicellulose enhances the elimination of lignin and increases the whiteness of said fiber.
Xylan decomposing enzyme called hemicellulase is commonly employed in paper/pulp industry, starch/baking industry, and the like.
Employed as the xylan decomposing enzymes may be those originated from microorganisms, animals, plants, and the like, and refined and unrefined products may be employed. These enzymes may be employed individually or in combination and may be successively. The added amount is between 0.01 and 10 percent by weight based on the dried weight of the fiber source.
The xylan decomposing activity of an enzyme may be examined employing the method described below as a simplified method. Namely, commercially available xylan (Sigma Co.), derived from oats, is suspended in an aqueous solution adjusted to optional pH so that the concentration is one percent by weight. After agar is added to obtain a concentration of 2 percent by weight, the resulting mixture is heated to between 90 and 100xc2x0 C., and an agar plate is prepared. The enzyme liquid is suitably diluted or concentrated, and the resulting liquid is spotted onto the agar plate. The spotted agar plate is maintained at optional temperature. After 24 hours, the agar plate is observed. When a clear zone is observed around the spotted area, it is judged that the enzyme has a xylan decomposing activity.
During an enzyme treatment, the concentration of raw material is generally between 0.1 and 20 percent by weight, and is preferably between 1 and 10 percent by weight. The more the pH and temperature conditions approach the optimum conditions of decomposition activity, the more effective results are obtained. However, it is unnecessary to stick to those, and conditions may be employed in any range in which the enzyme is allowed to work. Generally, conditions may be selected from a pH range of 3 to 11 and a temperature range of 10 to 90xc2x0 C. The treatment time depends on the treatment pH, the treatment temperature, and the amount of enzyme. Furthermore, it also depends on the type of raw materials such, as rice straw, wheat straw, bagasse, and the like and the degree of the pretreatment. When the treatment is carried out while stationary or being slowly stirred, the required treatment time is one hour at the shortest and about 10 days at the longest. Enzyme treatment conditions may be determined while considering the limitations in the practical production. It is desirous to set the optimal conditions after carrying out a preliminary test.
Furthermore, when in order to decompose oils, fats, or proteins incorporated in a raw material, an oil or fat decomposing enzyme, as well as a protein decomposing enzyme, is allowed to work in advance or at the same time, pulping may be more readily carried out. It is not preferred to employ a cellulose decomposing enzyme because such enzyme decomposes the fiber itself and decreases the yield as well as the strength of the pulp. However, for example, if the strength of the pulp is not critical, pulping may be readily carried out by allowing the cellulose decomposing enzyme to work prior or simultaneously. In such cases, the nearer the optimal conditions of decomposition activity from the characteristics of an employed enzyme approaches, the more effective are the results obtained. However, it is not required to stick to those, and any range may be employed in which the enzyme is allowed to react.
A raw material which has been subjected to enzyme treatment is often not yet in a state to be directly constituted into paper because fibers are still aggregated or non-fiber materials are still attached. Therefore, disaggregation as well as beating is carried out, and fibers are well separated and collected. The disaggregation as well as beating may be carried out employing a pulper, a beater, a refiner, a PFI mill, and the like. Disaggregation, as well as beating, is preferably carried out in alkali conditions with the purposes of allowing the material organization to swell further and of extracting lignin. However, said conditions are not to be limited. Further, in order to carry out those in the alkali conditions, it is preferred to employ a method in which a raw material is immersed into an alkali solution prior to carrying out the enzyme treatment. The alkali solution after use can allow to immerse subsequent raw material and can be repeatedly employed. Thus much less effluent is generated compared to conventional soda methods.
Separation may be carried out employing a rotating sieve, a flat screen, a pressure screen, and the like. Fiber portions and non-fiber portions are effectively separated by employing the same or different types of sieves in two or more levels.
Thereafter, pulp for paper and paper board may be prepared upon reduction bleaching and/or oxidation bleaching in accordance with conventional methods as required. For example, the reduction bleaching is carried out in such a manner that in the range of a pulp concentration of 3 to 5 percent, a pH of 5 to 6, and a temperature of 50 to 65xc2x0 C., sodium hydrosulfite is added in an amount of 0.5 to 1.0 percent by weight with respect to dry pulp, and the resulting mixture is processed for 0.5 to 1.0 hour.
Furthermore, oxidation bleaching may be carried out employing chlorine water, sodium hypochlorite, chlorine dioxide, hydrogen peroxide, and the like. For example, when sodium hypochlorite is employed, processing is carried out for 2 to 6 hours under a pulp concentration of 3 to 5 percent, a temperature of 25 to 50xc2x0 C., and an effective chlorine concentration of 2 to 9 percent. The oxidation bleaching is preferably carried out employing two or more types of compounds and a multi-step process. When compounds containing chlorine such as sodium hypochlorite, chlorine water, chlorine dioxide, and the like, are employed, an alkali extraction operation is preferably included.
The length of the natural fibers in the present invention is an average length of the fiber kneaded into a thermoplastic resin, and in the present invention, is preferably between 0.3 and 3.0 mm. Furthermore, cellulose based fibers (preferably natural fibers) having a water content of no more than 5 percent are preferably employed as raw material.
Employed as vegetable fibers may be various types of natural pulp. However in terms of strength, unbleached pulp is preferred irrespective of the origin of needle-leaf trees or broadleaf trees. Furthermore, from economical and environmental aspects, used Kraft paper waste, corrugated board paper waste, paper waste, such as newspapers, magazines, and the like may be employed.
Into a mixture comprised of a vegetable fiber and a thermoplastic resin in the present invention, optionally incorporated may be various additives, for instance, inorganic pigments such as carbon black and the like, organic pigments, light shielding materials such as a light shielding cellulose fiber and the like, lubricants, and the like. However, only a mixture comprised of a cellulose based fiber and a thermoplastic resin can fully achieve the object of the present invention.
The thermoplastic resins employed in the present invention are those which are comprised of no halogen atoms and exhibit fluidity upon heating. Specific examples include natural rubber, acrylate rubber, butyl rubber, nitrile rubber, butadiene rubber, isoprene rubber, styrene-butadiene rubber, urethane rubber, silicone rubber, acrylic rubber, neoprene rubber, epichlorhydrin, EPDM (ethylene-propylene-diene rubber), elastomers such as urethane elastomer and the like, polyethylene, polypropylene, polybutadiene, polybutene, shock-resistant ABS resin, polyurethane, ABS resin, cellulose acetate, amide resin, nitrocellulose, polystyrene, epoxy resin, phenol-formaldehyde resin, polyester, shock-resistant acrylic resin, ethylene-vinyl acetate copolymer, acrylonitrile-butadiene copolymer, polyvinyl acetate, and the like. Preferred as thermoplastic resins are polyolefin based resins such as polyethylene resins, polypropylene resins, polyethylene-vinyl acetate copolymers, which are not likely to generate toxic gasses except for carbon dioxide gas and water during incineration. Of polyethylenes, ethylene-xcex1-olefin copolymers are preferred which have a density in the range of 0.86 to 0.94 g/cm3, a melt index in the range of 0.01 to 40 g/10 minutes, and a main peak of DSC melting point of 50 to 115xc2x0 C. Particularly preferred are ethylene-xcex1-olefin copolymers prepared employing a metallocene catalyst as a polymerization catalyst. More preferably employed are copolymers of ethylene with 4-methylpentene, 1-hexene, or 1-octene 1 as xcex1-olefin, which are prepared employing a metallocene catalyst as a copolymerization catalyst, and have a density of 0.89 to 0.92 g/cm3, and a melt index of 5 to 25 g/10 minutes. Preferred are those which are obtained by copolymerizing 9 to 30 percent by weight of ethylene with xcex1-olefin in an amount to make the total percent by weight 100. The mix ratio of a vegetable fiber to a thermoplastic resin is preferably between 50 and 90 percent by weight from the aspects of injection molding properties, strength, and hardness, and is most preferably between 55 and 75 percent by weight. The production methods of molding mixtures comprised of a vegetable fiber and a thermoplastic resin are not particularly limited and any of several methods known in the art may be employed. For example, those obtained by shearing pulp, waste paper, and the like into pieces employing a shearing machine and a thermoplastic resin are well mixed at a temperature of at least 10xc2x0 C. higher than its melting point, and the resulting mixture is used to mold the desired parts.
In a thermoplastic composition comprised of at least 50 percent of the natural fiber of the present invention, as well as a thermoplastic resin, preferably employed as the thermoplastic resin, is a polyolefin based resin. The polyolefin based resin as described herein denotes a resin comprising a large portion of polyolefin and mainly exhibiting properties of a polyolefin resin, and polyolefin may be employed individually or in combination.
Namely, the polyolefin based resins include an individual chemically modified polyolefin (hereinafter referred to as a modified polyolefin), or those prepared by combining the modified polyolefin with an unmodified polyolefin resin (hereinafter referred to as polyolefin resin, and separated from the polyolefin based resin), further include those combined with thermoplastic rubber such as polyolefin elastomer, and the like.
Namely, the polyolefin resins or polyolefin based resins preferably employed in the present invention imply polymers comprising polyolefin as the main component and resins comprised of mixtures thereof, and the like. It does not really matter that those are olefin homopolymers, copolymers of olefin with the other olefin, various copolymers with other monomers, others such as differences (straight chain, branched chain, stereoscopic regularity, and the like) in chemical structures, and the like.
Generally employed as the polyolefin resins are polypropylene having an isotactic structure as the main component, low density or high density polyethylene, copolymers of these with olefin other than these, and mixtures thereof. Specifically employed are the aforementioned polypropylene homopolymer resins, polypropylene copolymer resins, or resins comprised of polypropylene as the main component.
Furthermore, the modified polyolefins as described herein are those in which polyolefin resins are allowed to have a polar group in order to obtain a firm bond of the polar group of a vegetable fiber comprising cellulose as the main component with the polyolefin resin. Preferably employed as the polar group are carboxylic acids or anhydrides thereof. In order to introduce these polar groups, preferably employed are monocaroxylic acids, polycarboxylic acids, or anhydrides thereof. Preferably employed as dicarboxylic acids or anhydrides thereof may be listed, for example, maleic acid, fumaric acid, maleic anhydride, or alicyclic dicarboxylic acids or anhydrides thereof which have a cis type double bond in the ring, for example, cis-4-cyclohexane-1,2-dicarboxylic anhydride (generally called tetrahydrophtalic anhydride), cis-4-cyclohexane-1,2-dicarboxylic acid (generally called tetrehydrophthalic acid), endo-bicyclo(2,2,1)-5-heptene-2,3-dicarboxylic acid (generally called himic acid), endo-bicyclo(2,2,1)-1,2,3,4,7-hexachloro-2-heptene-5,6-dicarboxylic anhydride (generally called chlordenic anhydride), endo-bicyclo(2,2.1)-hexachloro-2-heptene-6,6-dicarboxylic acid (generally called chlordenic acid), and the like.
Accordingly, polyolefin based resin compositions preferably exhibit high fluidity, either when polyolefin resins are employed alone, or when those are combined with modified polyolefin, polyolefin elastomer and the like with the purpose of the enhancement of mechanical properties.
In the present invention, a thermoplastic composition preferably has a melt index (occasionally referred to as MI) of 20 to 100. Said MI is an index measured by Condition 4 in Table 1 in JIS K7210 or conditions in Table 1 in ASTMD 1238, both conditions being well known in this industry.
Thermoplastic resins are not particularly limited. However, when environmental adaptability as waste, which is one of the objects of the present invention, is to be taken into account, polyethylene resins and polyethylene-vinyl acetate copolymers are preferred which generate no toxic gas during incineration.
Furthermore, a molding material preferably comprises at least one selected from the compounds represented by general formulas (I) through (V) or tetramethylolcyclohexanol.
Next, the compounds represented by general formulas (I) through (V) will be described.
In general formula (I), R1 represents a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an acylamino group, or an amino group, and R2 represents a hydrogen atom, an alkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, a carbamoyl group, an amino group, or an amidino group. Furthermore, R1 and R2 may bond to form a ring. Further, these groups may have a substituent. X represents xe2x80x94CH2xe2x80x94 or xe2x80x94NHxe2x80x94.
In general formula (II), R3, R4 and R5 may be the same or different, and each represents a hydrogen atom, an alkyl group, an alkenyl group, an aralkyl group, an aryl group, or an acyl group.
R6 and R7 each represents a hydrogen atom or an alkyl group (listed as examples are the similar groups to those described for R3, R4, and R5).
Compounds represented by general formula (II) include polymer-shaped compounds, which bond to a polymer chain (for instance, a polyethylene chain and a polypropylene chain) via a group represented by R3, R4, and R5. Further, in this case, said compounds included those in which xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94, xe2x80x94CONHxe2x80x94 and the like, as a linkage group, form a polymer chain with the group of R3, R4, and R5.
In general formula (III), R8 represents a hydrogen atom, an alkyl group, or an aryl group. Furthermore, R8 may be a group which forms naphthalene ring together with a phenyl ring. Said alkyl group and aryl group include those having a substituent. xe2x80x9cnxe2x80x9d represent an integer of 2 to 4.
In general formula (IV), R9 represents a hydrogen atom or a substituent. Cited as substituents are, for example, an alkyl group, an aryl group, a cycloalkyl group, an acyl group, a carbamoyl group, a sulfamoyl group, and an alkoxycarbonyl group. These groups may further have a substituent (for example, a carboxyl group, a sulfo group, a hydroxyl group, an amino group, and the like).
R10 represents a hydrogen atom or a substituent. Cited as substituents are, for example, an alkyl group, an aryl group, a cyano group, a carbamoyl group, a carboxyl group, an alkoxycarbonyl group, an acyl group, a haloalkyl group, a nitro group, a sulfamoyl group, an alkylsulfamoyl group, an alkylsulfonyl group, and the like.
In general formula (V), R11 and R12 each represents a hydrogen atom or a substituent, and R13 represents a hydrogen atom or an alkyl group. Z represents a hydrogen atom, an alkyl group, an aryl group, xe2x80x94SO2R14, or xe2x80x94SO2N(R14) (R15). R14 represents an alkyl group, an aryl group, or a heterocyclic ring group, and R15 is as defined above for R13. Furthermore, R13 and Z may be joined together to form a ring.
Cited as examples of substituents represented by R11 are a straight or branched alkyl group having from 1 to 18 carbon atoms, a cycloalkyl group having from 5 to 7 carbon atoms, an aryl group, a 5-membered or 6-membered heterocyclic ring group, or xe2x80x94SO2R16, xe2x80x94SO2N(R16) (R17), xe2x80x94COR16, xe2x80x94CON(R16) (R17), xe2x80x94COOR16, xe2x80x94CONHNHR18, xe2x80x94C(xe2x95x90NH)NH2, xe2x80x94CSNHR18, xe2x80x94CSNHNHR18 (wherein R16 represents an alkyl group, an aryl group, or a heterocyclic ring group, R17 represents a hydrogen atom or an alkyl group, and R18 represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic ring group).
These substituents may further have a substituent. Listed as examples of these substituents are an alkyl group, an acylamino group, a sulfonamido group, a carbamoyl group, a sulfamoyl group, an alkoxycarbonyl group, a nitro group, a cyano group, a hydroxyl group, a carboxyl group, a sulfo group, a halogen atom, and the like. Of these, a sulfo group, a carboxyl group, and a hydroxyl group are most preferred.
Preferred as R11 are a hydrogen atom, an alkyl group, an aryl group, an alkylsulfonyl group, an acyl group, a carbamoyl group, and an alkoxycarbonyl group.
Cited as examples of substituents represented by R12 are a straight or branched alkyl group having from 1 to 18 carbon atoms, a cycloalkyl group having from 5 to 7 carbon atoms, an aryl group, an aryl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an acyl group, an amino group, an alkylamino group, an arylamino group (for example, an anilino group and the like), an acylamino group, a sulfonamido group, a carbamoylamino group, a sulfamoylamino group, an alkoxycarbonylamino group, a cyclic amino group, a carboxyl group, a cyano group, or the like.
These substituents may further have a substituent. Cited as examples of these substituents are ones, which are the similar to those described in R11. Preferred as R12 are a hydrogen atom, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a carboxyl group, an acylamino group, a carbamoylamino group, a sulfonamido group, a sulfamoylamino group, and an alkoxycarbonylamino group, and those particularly preferred are an alkyl group, an acylamino group, a carbamoylamino group, a sulfonamido group, and an alkoxycarbonylamino group.
Listed as examples of alkyl groups represented by R12 are straight or branched alkyl groups having from 1 to 18 carbon atoms. These may further be substituted with a halogen atom, an alkoxy group, an aryloxy group, an acylamino group, a sulfonamido group, a carbamoyl group, a sulfamoyl group, an alkoxycarbonyl group, a nitro group, a cyano group, a hydroxyl group, a carboxyl group, a sulfo group, an amino group, an alkylamino group, a dialkylamino group, and the like.
Z represents a hydrogen atom, an alkyl group, an aryl group, xe2x80x94SO2R13, or xe2x80x94SO2N(R14) (R15) (wherein R14 represents an alkyl group, an aryl group, or a heterocyclic ring group, and R15 is as defined above for R13). Cited as these examples are a methyl group, an ethyl group, a butyl group, a methoxymethyl group, a cyanoethyl group, a phenyl group, a methylsulfonyl group, an ethylsulfonyl group, a butylsulfonyl group, benzenesulfonyl group, a dimethylsulfamoyl group, a diethylsulfamoyl group, and the like. Z is preferably an alkyl group or an alkylsulfonyl group.
Representative examples of compounds represented by general formulas (I) through (V) are illustrated below, however the present invention is not limited these. 
Many compounds described above are commercially available, and those, which are not commercially available, may readily be synthesized according to methods described in patents and publications shown below.
Compounds I-7 and I-8 can readily be synthesized according to methods described in Bulletin of the Chemical Society of Japan, Volume 39, pages 1559 to 1567, 1734 to 1738 (1966), Chemische der Berichte, Volume 54, pages B1802 to 1833, 2442 to 2479 (1921), Beilstein Handbuch der Organischen Chemie, page H98 (1921), and the like.
Compound I-13 is an oligomer or polymer having one repeating unit.
Compound I-19 can be synthesized according to a method described in Beilstein Handbuch der Organischen Chemie (which is described above), First Enlarged Edition Volume 4, page 354, the same Volume 3, page 63 and the like.
Compounds II-1 and II-11 can be synthesized according to methods described in British Patent No. 717,287, U.S. Pat. Nos. 2,731,472 and 3,187,004, H. Pauly, Chem. Ber., 63B, page 2063 (1930), F. B. Slezak, J. Org. Chem., 27, pages 2 to 181 (1962), J. Nematollahl, J. Org. Chem., 28, page 2378 (1963), and the like. Furthermore, by allowing glycoluril to undergo alkylation, acylation, hydroxymethylation, alkoxymethylation, halomethylation, and the like, corresponding alkyl, acyl, hydroxymethyl, alkoxymethyl and halomethyl derivatives are obtained.
Compounds IV-1 through IV-30 can readily be synthesized according to methods described in Japanese Patent Publication Open to Public Inspection Nos. 51-77327 and 62-273527, British Patent 585,780, and the like.
Compounds V-1 through V-24 can readily be synthesized in accordance with methods described in Berichte der Deutschen Chemischengesellschaft 57, page 332 (1924), Annalen der Chemie, 52, page 622 (1936), ibid., 397, page 119 (1913), ibid., 568, page 227 (1950), Journal of the American Chemical Society, 734, page 664 (1951), and the like.
Of these, I-1 (dimedone) and tetramethylolcyclohexanol are particularly preferred.
A phenol resin may further be added in addition to these compounds.
Namely polyolefin resins or polyolefin based resins preferably employed in the present invention imply copolymers comprised of polyolefins as the main component and resins comprised of mixtures thereof. Olefin homopolymers, copolymers of olefin with another olefin, or various copolymers of olefin with other monomers, and others having different chemical structures (straight chain, branched chain, stereoscopic regularity, and the like) are not concerned.
In polyolefin resins, commonly and preferably employed are polypropylenes having an isotactic structure as the main structure, low density or high density polyethylenes, copolymers of olefin with one other than the above, and mixtures thereof. Specifically, the aforementioned polypropylene homopolymer resins, polypropylene copolymer resins or resins comprised of polypropylene as the main component are preferably employed.
Furthermore, the modified polyolefins as described herein are those in which polyolefin resins are allowed to have a polar group in order to allow the polar group of a vegetable fiber comprising cellulose as the main component to firmly bond to the polyolefin resin. Preferably employed as the polar group are carboxylic acids or anhydrides thereof. In order to introduce these polar groups, preferably employed are monocaroxylic acids, polycarboxylic acids, or anhydrides thereof. Preferably employed as dicarboxylic acids or anhydrides thereof may be listed, for example, maleic acid, fumaric acid, maleic anhydride, or alicyclic dicarboxylic acids or anhydrides thereof which have a cis type double bond in the ring, for example, cis-4-cyclohexane-1,2-dicarboxylic anhydride (generally called tetrahydrophtalic anhydride), cis-4-cyclohexane-1,2-dicarboxylic acid (generally called tetrehydrophthalic acid), endo-bicyclo(2,2,1)-5-heptene-2,3-dicarboxylic acid (generally called himic acid), endo-bicyclo(2,2,1)-1,2,3,4,7-hexachloro-2-heptene-5,6-dicarboxylic anhydride (generally called chlordenic anhydride), endo-bicyclo(2,2.1)-hexachloro-2-heptene-6,6-dicarboxylic acid (generally called chlordenic acid), and the like.
In order to uniformly knead at least 50 percent of a natural fiber with a thermoplastic resin, it is possible to employ devices and methods such as a high speed fluid mixer, an extruder, and combinations thereof, as they are, which are generally used to knead a resin with a filler. However, in order to allow a cellulose fiber to exhibit its features, methods are preferred which results in good dispersion of fibers and results in neither damage nor carbonization of the fiber. For such reasons, a petroleum- resin, rosin or a rosin derivative is preferably incorporated into a molding material in an amount of 0.1 to 40 percent by weight of the total weight.
Rosin as described herein denotes a representative one which is obtained by steam-distilling a pine resin to remove its volatile turpentine oil. In the present invention, employed may be its derivatives such as hydrogenated compounds, disproportionated compounds, glycerin esters, maleic acid modified parts, and the like. These have a softening point or a melting point of 50 to 130xc2x0 C.
The petroleum resin is a resin prepared by polymerizing an unsaturated hydrocarbon mixture obtained during petroleum refining, cracking and the like in the presence of a catalyst, and has a melting point of about 60 to about 120xc2x0 C. In such respect, the petroleum resin has physical properties similar to the rosin or derivatives thereof. Further, employed as plasticizers may be those for polyolefin. For example, butyl stearate as well as polyisobutylene is representative and in addition, employed may be phthalic acid esters of higher alcohols, which are plasticizers for vinyl chloride resins.
Incorporated as other additives into the thermoplastic composition may be compounds described below.
Employed as inorganic fillers may be those commonly used such as calcium carbonate, magnesium silicate, aluminum silicate, barium sulfate, calcium sulfate, and the like, and those having an average particle diameter of no more-than 10 xcexcm are preferred. Employed as synthetic rubber are ethylene-propylene rubber (EPR), third component containing ethylene-propylene terpolymer, butyl rubber, polybutadine rubber, and the like. In order to uniformly mix the polyolefin based resin with the aforementioned various additives, devices and methods generally employed to mix a resin with a filler, such as a Banbury mixer, a roll mixer, a kneader, an extruder, a high speed rotary mixer, and combinations thereof, may be directly employed without any modifications. In the mixture prepared by combining a polyolefin resin only with a vegetable fiber without adding rosin and plasticizers, uniform dispersion of the vegetable fiber is fairly difficult, and the affinity between the polyolefin resin and the vegetable fiber is small. As a result, the strength and the like degrade and the uniformity of product quality is lost. Thus commercially viable materials are not obtained. In this case, it is possible to improve the strength as well as the uniformity of product quality to a certain level by decreasing the combined amount of the vegetable fiber. However, it is difficult to fully achieve the desired objects due to a decrease in rigidity, heat resistance, painting properties, and the like. In order to improve dispersibility of the vegetable fiber to increase its combining power with the polyolefin based resin and to increase the combined amount of the vegetable fiber, the combination of rosin or, its analog, and a plasticizer in the composition of the present invention is extremely important.
Furthermore, as a molding material, it is desirous that after 1 gram of the molding material is kept standing at ambient conditions of 23xc2x0 C. and 55 percent RH for 24 hours, the resulting material is placed into a 30-cc vessel and sealed tightly, and when the vessel is heated for 30 minutes in an oil bath maintained at 120xc2x0 C., the amount of furfural generated in the vessel is no more than 10 xcexcg/g of the molding material.
Based on the aforementioned constitution, the fog minimizing effect as well as the offensive odor minimizing effects becomes more marked, and in addition, such effects may be readily achieved. Furthermore, it is preferred to decrease the amount of hemicellulose in a cellulose based fiber, to set washing conditions for the cellulose based fiber, or to set kneading conditions such as the kneading temperature and the like of a thermoplastic resin with a cellulose based fiber so as to satisfy the aforementioned constitution. The kneading temperature is preferably between 70 and 150xc2x0 C., and is more preferably between 70 and 120xc2x0 C.
Furthermore, as a molding material, when 0.3 gram of the aforementioned molding material is combusted at a temperature of 850xc2x0 C. and an air flow rate of 300 ml/minute in a tube-shaped electric furnace in accordance with JIS K 2541, combustion heat detected by a calorimeter specified in JIS M 8814 is preferably between 5,000 and 8,000 cal/g.
Furthermore, employed as a molding material is a test piece (having two holes with a diameter of 5 mm and a distance of 11 mm between the hole centers) obtained by machining the aforementioned molding material having length 114 mmxc3x97width 33 mmxc3x97thickness 10 mm into a compact tension shape in accordance with ASTM-D5045 Standard. A tool is inserted between the aforementioned two holes in accordance with ASTM-D5045 Standard employing an Instron type tester, the wedge type cut is pulled so as to open it and the obtained breaking tenacity value is preferably between 0.5 and 50 kg/mm3/2.
Furthermore, the linear expansion coefficient of said molding material is preferably below 12xc3x9710xe2x88x925/xc2x0 C., and is more preferably below 7xc3x9710xe2x88x925/xc2x0 C.
Furthermore, the heat deformation temperature of said molding material, at a bending stress of 18.6 kgf/cm2 in accordance with ASTM-D648, is preferably at least 50xc2x0 C., and is more preferably at least 70xc2x0 C.
The fiber is preferably subjected to washing before kneading. Example of the preferable washing method is as follows. The fiber is sintered into water of 40 to 75xc2x0 C. in an amount of twice of the weight of the fiber, after ten minutes to one hour, preferably ten minutes, then the fiber is taken out and squeezed. The process is repeated 3 to 10 (preferably 3 to 5) times.
Furthermore, the volume resistivity of said molding material, measured in accordance with JIS K 6911, is preferably at least 109 xcexa9 cm, and is more preferably at least 1016 xcexa9 cm.
In the present invention, a natural fiber and a thermoplastic resin are first kneaded employing a non-screw type mixer such as a tumbler mixer, a high speed rotary mixer, a V blender, a ribbon blender, a Banbury mixer, and the like. Of these, the Banbury mixer is most preferred. Furthermore, as preferable kneading conditions, the operation is carried out at 70 to 150xc2x0 C., and is more preferably carried out at 70 to 120xc2x0 C. It is preferred to maintain the kneading temperature in this range, because the generation of furfural may be decreased and fogging as well as offensive odor may be effectively prevented or minimized. Molding such as injection molding and the like is preferably carried out in the range of 70 to 150xc2x0 C., more preferably 100 to 130xc2x0 C. It is more preferred to heat at 50 to 80xc2x0 C. for 1 or 2 days.
The mixing ratio of a vegetable fiber with a thermoplastic resin is preferably between 50 and 90 percent by weight from the aspects of injection molding properties, strength, and combustion calories, and is most preferably between 55 and 75 percent by weight. Production methods for mixed molding parts comprised of the vegetable fiber and the thermoplastic resin are not particularly limited, and any of the several methods known in the art may be employed. For example, those obtained by shearing pulp, waste paper, and the like into small pieces employing a shearing machine and a thermoplastic resin are well mixed at a temperature at least 10xc2x0 C. higher than its melting point, and the resulting mixture is used to be molded into desired products.
Specifically, during injection molding, it is necessary to regulate temperature conditions so that materials flow sufficiently into all crevices of the molding die.
Mixture molding parts comprised of a vegetable fiber and a thermoplastic resin exhibit a markedly small contraction ratio after injection molding compared to plastics. Accordingly, it is possible to enhance molding and machining efficiency (being a decrease in cooling time) and to improve dimensional stability followed by markedly overcoming light shielding problems and removing problems of photosensitive materials due to poor assembly and deformation. Furthermore, affinity with adhesives is improved due to the presence of cellulose components, and adhesion is enhanced compared to plastics. Thus, connection with other parts such as a paper-made body is easily carried out to increase the strength of the connected parts.
In the present invention, a mixed molding material consisting of a vegetable fiber and a thermoplastic resin may be employed in some portion of the component constituting a molding material or it may be employed to constitute an entire molding material. Said mixed molding material is preferably employed to produce parts which require a relatively high strength and hardness in terms of the structure.
The molding material of the present invention, when employed as various resin materials for photosensitive photographic materials, may sufficiently exhibit the effects of the present invention. Said material may be employed for a body and the like for a lens-fitted film, and may preferably be employed for its front and rear covers.